Fix for bug 4812. Support last-child and last-of-type CSS3 selectors.  Brings Acid3 score up to 68/100.

        Reviewed by olliej

        Added fast/css/last-child-pseudo-class.html, fast/css/last-of-type-pseudo-class.html

        * css/CSSGrammar.y:
        * css/CSSSelector.cpp:
        (WebCore::CSSSelector::extractPseudoType):
        * css/CSSSelector.h:
        (WebCore::CSSSelector::):
        * css/CSSStyleSelector.cpp:
        (WebCore::CSSStyleSelector::checkOneSelector):

LayoutTests:

        Fix for bug 4812.  Support last-child and last-of-type (and make sure they are properly dynamic).

        Reviewed by olliej

        * fast/css/last-child-pseudo-class.html: Added.
        * fast/css/last-of-type-pseudo-class.html: Added.
        * platform/mac/fast/css/last-child-pseudo-class-expected.checksum: Added.
        * platform/mac/fast/css/last-child-pseudo-class-expected.png: Added.
        * platform/mac/fast/css/last-child-pseudo-class-expected.txt: Added.
        * platform/mac/fast/css/last-of-type-pseudo-class-expected.checksum: Added.
        * platform/mac/fast/css/last-of-type-pseudo-class-expected.png: Added.
        * platform/mac/fast/css/last-of-type-pseudo-class-expected.txt: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@29933 268f45cc-cd09-0410-ab3c-d52691b4dbfc